Fix command-line argument passing to pre-fill UI

When running the inspector with command-line arguments (e.g.,
`npx @modelcontextprotocol/inspector node build/index.js arg1 arg2`),
the command and arguments were not being properly passed through to
the UI for pre-filling.

Changes:
- cli.ts now passes command and args to start.js
- start.js uses --command for the command and --args for arguments
- Server parses the new --command parameter
- /config endpoint returns correct values for UI pre-filling

This ensures the UI correctly displays the command and arguments
passed on the command line instead of showing old localStorage values.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

cli/src/cli.ts

@@ -66,8 +66,21 @@ async function runWebClient(args: Args): Promise<void> {
     abort.abort();
   });
 
+  // Build arguments to pass to start.js
+  const startArgs: string[] = [];
+
+  // Pass environment variables
+  for (const [key, value] of Object.entries(args.envArgs)) {
+    startArgs.push("-e", `${key}=${value}`);
+  }
+
+  // Pass command and args (using -- to separate them)
+  if (args.command) {
+    startArgs.push("--", args.command, ...args.args);
+  }
+
   try {
-    await spawnPromise("node", [inspectorClientPath], {
+    await spawnPromise("node", [inspectorClientPath, ...startArgs], {
       signal: abort.signal,
       echoOutput: true,
     });